An official investigation has been launched into a Christchurch construction company which allegedly underpaid two migrants, and into the licensed immigration adviser who helped them obtain a visa.

Filipino men Emmanuel Francisco Jr and Carlos Claveron told The Press earlier this month that they had been left out of pocket after being underpaid for their work as a painter and a builder, respectively, for TCL Painting and Construction.

They also claimed they each paid about $14,000 in fees to licensed immigration consultant Rosemarie Scholes to secure a job and a visa in New Zealand.

Labour MP Darien Fenton brought up the workers' case in Parliament last week through several questions to the Minister of Labour.

"What priorities has his [the Minister of Labour's] Labour Inspectorate given the case of Carlos Claveron Emmanuel Francisco, who were recruited from the Philippines to work in the Christchurch rebuild for $18 and hour, but after they started working in New Zealand, their employer demanded that they repay $3 an hour in cash," Fenton asked in Parliament.

"What advice does he have from the Minister of Immigration about workers like Carlos and Emmanuel, who came to New Zealand after paying $15,000 to an immigration adviser, who was publicly reported as scamming other Filipino workers last March . . . but is still operating as a licensed immigration adviser?"

The minister's representative answered he could not comment on individual cases but immigration officials confirmed yesterday an investigation into Scholes and into TCL Construction was under way.

TCL owner Them Cuoi Ly, a resident from Cambodia, who started his company in Christchurch a year ago, declined to comment on the investigation. He told The Press earlier this month that he reduced the workers' wages because they were not qualified to work in New Zealand.

Scholes, the immigration adviser, did not return calls, but rejected the workers' claims on TVNZ this week. She said no-one had complained directly to her and said her firm's fees were "negotiable, fair, and reasonable".

Last year she was found guilty of breaching the Immigration Advisers Authority (AAI) code of conduct after she duped a Filipino nurse into paying thousands of dollars for an English-language programme the adviser had a financial interest in.

The Press also revealed last year details of a recording in which Scholes offered $3000 to $4000 to a businessman posing as a recruiter of Filipino workers to "clip the ticket" on upfront fees paid by Filipino workers to secure employment in New Zealand.

Fenton told The Press she had been actively following Claveron and Francisco's case. "The employer has clearly broken the law, and I want action from the [MBIE] labour inspectorate on that.

"We are asking migrants to come to New Zealand to help with the Christchurch rebuild and we're allowing for them to be ripped off by immigration advisers and employers who break the law - that's completely unacceptable."

She said the labour inspectorate needed to take a proactive role in preventing migrant exploitation.

"Our whole system relies on workers coming forward and that is very difficult for them to do.

"What we need in Christchurch is a large, well-resourced labour inspectorate, who can check every single migrant worker's contract and arrangement."

The department of labour was "incredibly under-resourced", with only 35 inspectors for the whole country.

Changing the law was not going to make any difference, Fenton said, "unless we have people enforcing the law".